Recent years have been a considerable increase in the use of service vehicles in the servicing of remotely located equipment, off the road vehicles and the like. The service vehicles are adapted to transport servicing materials and/or equipment whereby routine operations and maintenance may be performed on site on the equipment or other vehicle to be serviced.
The service vehicles employed may be extremely simple to quite complex, ranging from a farmer's pick-up truck provided with a fuel reservoir for refueling tractors and/or combines in the field to special operations servicing vehicles which are capable of providing numerous servicing operations on remotely located machinery. For example, service vehicles have been utilized to provide a means of servicing remotely located equipment in terms of providing lubrication therefor. Typically, such vehicles are provided with a power take off to a fixed displacement hydraulic pump which in turn drives an air compressor. The air compressor is then used to provide pneumatic energy which is utilized in transporting the lubricants from storage locations on the truck to a point of use through suitable conduits.
Though such vehicles are capable of performing their intended function, they leave a lot to be desired. The utilization of a fixed displacement hydraulic pump to drive the air compressor requires unnecessary use of engine horsepower to maintain the compressor operable. Typically air pumps powered by the compressed air from the compressor for transporting lubricants are not particularly efficient and the ever present problem of condensate in compressed air lines could unexpectedly and undesirably render the service vehicle inoperative to perform the servicing function due to freezing of condensate in such air lines.
The present invention is directed to overcoming one or more of the above problems.